WO2011078578A2

WO2011078578A2 - Power control apparatus and power control method for construction machinery

Info

Publication number: WO2011078578A2
Application number: PCT/KR2010/009207
Authority: WO
Inventors: 손원선; 박덕우; 방재석
Original assignee: 두산인프라코어 주식회사
Priority date: 2009-12-24
Filing date: 2010-12-22
Publication date: 2011-06-30
Also published as: US20120251332A1; BR112012015598A2; CN102713089A; EP2518222A4; WO2011078578A3; BR112012015598B1; US8720629B2; CN102713089B; EP2518222A2; EP2518222B1

Abstract

According to one aspect of the present invention, a power control apparatus for construction machinery comprises: an engine (10) connected to a hydraulic pump (20) to drive the hydraulic pump (20); and a control unit (60), which calculates an engine load ratio, defined as a ratio of a load torque of the engine (10) to the maximum torque of the engine (10), calculated from an input target engine RPM, and calculates an engine RPM command value in proportion to the engine load ratio, such that the engine (10) can be driven at the target engine RPM, and outputs the calculated command value to the engine (10). According to another aspect of the present invention, a hydraulic pump control apparatus controls the hydraulic pump (20) driven by the engine (10), and comprises: a horsepower control unit (30), which varies the swash plate of the hydraulic pump (20) so as to vary the required horsepower of the hydraulic pump (20); a pressure sensor (50) for sensing a load pressure (Pd) of working oil discharged from the hydraulic pump (20); and a control unit (60), which calculates a target required horsepower of a pump from the load pressure (Pd) sensed by the pressure sensor (50), and controls the horsepower control unit (30) such that the required horsepower of the hydraulic pump (20) gradually becomes closer to the target required horse power of a pump during a preset time (Δt).

Description

Power control device and power control method for construction machinery

The present invention relates to a power control device for a construction machine, such as an excavator, in particular, power control of a construction machine that can improve the fuel economy by controlling the rotational speed of the engine according to the load ratio of the engine so that the engine is constantly driven at the target rotational speed Relates to a device.

In addition, the present invention relates to a power control device and a control method of a construction machine, such as an excavator, in particular, a power control device of a construction machine that can prevent the hydraulic shock by gradually increasing the pump required horsepower according to the load pressure of the hydraulic pump And a control method.

In general, a construction machine such as an excavator drives a plurality of work devices such as a boom, an arm, and a bucket by using hydraulic oil discharged from a variable displacement hydraulic pump directly connected to an engine.

The discharge flow rate of the hydraulic pump is controlled by various variables to satisfy various conditions such as work efficiency and fuel economy.

More specifically, the control method of the hydraulic pump is a flow control for controlling the discharge flow rate in accordance with the operation signal input from the operation unit (flow control) and the hydraulic pump in accordance with the discharge pressure of the hydraulic pump so that the required horsepower of the hydraulic pump is constant Constant horse power control for controlling the discharge flow rate and power shift control for controlling the discharge flow rate of the hydraulic pump in accordance with the load state of the engine.

The hydraulic pump is provided with a regulator for the control method as described above, the regulator is a work flow rate control unit for the work flow control, the back horsepower control unit for the back horsepower control, and the horsepower control (power shift control) It includes a horsepower control for. The working flow rate adjusting unit receives the center bypassed negative cone pressure, the pilot pressure of the operation unit, or the load sensing pressure of each actuator to control the discharge flow rate of the hydraulic pump. The back horsepower control unit receives the discharge pressure (load pressure) of the hydraulic pump to control the discharge flow rate of the hydraulic pump according to the set horsepower diagram. Finally, the horsepower control unit controls the discharge flow rate of the hydraulic pump according to the target engine rotation speed set by the dial gauge of the engine and the load of the engine calculated from the current engine rotation speed.

In the power control device as described above, as shown in FIG. 1, when the operation amount of the operation unit is rapidly increased, an operation signal is input to the working flow control unit so that the flow rate of the hydraulic pump is rapidly increased, thereby discharging the hydraulic pump. As the pressure increases rapidly, the required horsepower of the hydraulic pump increases rapidly. Then, the rapidly increased discharge pressure of the hydraulic pump is input to the back horsepower control unit to start to reduce the discharge flow rate of the hydraulic pump.

However, due to the responsive delay time of the back horsepower control unit, the flow rate of the hydraulic pump is reduced by the back horsepower control unit after a certain time from the time when the discharge pressure of the hydraulic pump increases. In this way, the discharge pressure of the hydraulic pump continuously increases during the time when the back horsepower control time is delayed, and the hydraulic shock is generated. Due to such a hydraulic shock, a section in which the required horsepower of the hydraulic pump is rapidly increased, as in section A of FIG. 1.

As such, the sudden increase in horsepower required of the hydraulic pump acts as a large load on the engine, so that the rotation speed of the engine drops rapidly below the set target rotation speed. As such, when the engine rotation speed is sharply reduced, not only the amount of smoke increases but also the vibration increases. In particular, the engine, as in section B of FIG. 1, the engine power increase rate is low in the section in which the turbocharger operation reaches a steady state (turbo charger time lack section), so that the engine rotation speed is further reduced and the amount of smoke is reduced. And the vibration becomes larger.

On the other hand, if the rotational speed of the engine is sharply lowered from the target rotational speed, the horsepower control unit lowers the driving of the hydraulic pump from the highest horsepower (200mA) to the lowest horsepower (600mA) to increase the engine rotational speed. As a result, the flow rate of the hydraulic oil discharged from the hydraulic pump is reduced, which lowers the working efficiency of the construction machine.

2 is an isometric horsepower diagram schematically showing the process as described above. Referring to Figure 2, due to the time delay of the horsepower control time, it can be seen that the flow rate and the pressure is returned to the back horsepower diagram again after the discharge pressure of the hydraulic pump rapidly increases, as in the C diagram.

Summarizing the problems caused by the conventional power control device as described above, due to the time delay of the back horsepower control time by the back horsepower control unit, a hydraulic shock is generated in which the required horsepower of the hydraulic pump increases sharply. The engine's rotational speed drops sharply to increase the amount of smoke and vibration.In order to restore the engine's rotational speed to the target rotational speed, the required horsepower of the hydraulic pump is drastically reduced in the process of driving the hydraulic pump to the minimum horsepower. There is a problem that the working performance of the machine is reduced.

In addition, when the horsepower control of the engine is described in more detail, the control unit controls the horsepower control unit to reduce the flow rate of the hydraulic pump to return the engine rotational speed to the target rotational speed if the engine rotational speed is less than the target rotational speed Outputs Then, when the discharge flow rate of the hydraulic pump is controlled so that the rotation speed of the engine becomes larger than the target rotation speed, the control signal is output to the horsepower control unit again to increase the flow rate of the hydraulic pump. In this way, the rotational speed of the engine is manually controlled by the load of the hydraulic pump. As shown in FIG. 3, when the engine load ratio (load torque of the engine with respect to the engine maximum torque) increases, the rotational speed of the engine approaches the target rotational speed. As the engine load ratio decreases, the engine speed becomes higher than the target engine speed. As a result, even when the load transmitted from the hydraulic pump to the engine is small, energy loss is increased because the rotation speed of the engine is maintained high.

The present invention has been made in view of the above-described point, and an object thereof is to provide a power control device for a construction machine that can improve fuel efficiency by maintaining a constant rotation speed of an engine at a target rotation speed.

Another object of the present invention is to provide a hydraulic pump power control apparatus for a construction machine that can prevent the occurrence of hydraulic shock due to a time delay at the time of controlling horsepower.

Still another object of the present invention is to provide a power control device for a construction machine that can improve the working performance of a construction machine by preventing a sudden drop in the rotational speed of the engine even when a large operation amount is input from the operation unit.

Power control device for a construction machine according to an aspect of the present invention for achieving the above object is an engine (10) connected to the hydraulic pump 20 to drive the hydraulic pump (20); And an engine load ratio defined by a ratio of the load torque of the engine to the engine maximum torque calculated from the input engine target rotation speed, and the engine rotation speed command value according to the engine load ratio such that the engine is driven at the target rotation speed. It includes a control unit 60 for calculating the output to the engine.

According to an embodiment of the present invention, the control unit 60 calculates the engine maximum torque from the engine target rotation speed, calculates the engine load torque from the fuel injection amount command value output to the engine 10, and An engine controller (61) for calculating and outputting the engine load ratio from the calculated engine maximum torque and the engine load torque; And an equipment controller 62 which calculates the engine speed command value from the engine load ratio output from the engine controller 61 and outputs the engine speed command value to the engine controller 61, wherein the engine controller 61 is the equipment controller. The fuel injection quantity command value is calculated and output to the engine 10 in accordance with the engine rotation speed command value transmitted from 62.

The power control device as described above comprises a horsepower control unit 30 for varying the horsepower of the hydraulic pump 20 by varying the swash plate angle of the hydraulic pump 20; And a pressure sensor 50 for detecting a load pressure Pd of the hydraulic oil discharged from the hydraulic pump 20, wherein the equipment controller 62 has a load pressure sensed by the pressure sensor 50. The target pump required horsepower is calculated from Pd, and the horsepower control unit 30 is controlled so that the required horsepower of the hydraulic pump 20 gradually approaches the target pump required horsepower for a predetermined time Δt.

On the other hand, when the load pressure Pd detected from the pressure sensor 50 is the no load pressure Pd1, the target pump required horsepower is set to the minimum horsepower (POmin), the load detected from the pressure sensor 50 If the pressure is the maximum set pressure (Pd2), the target pump required horsepower is set to the maximum horsepower (POmax), the maximum set pressure (Pd2) is the starting horsepower control starting point of the maximum horsepower (POmax) of the hydraulic pump 20 Is set equal to or smaller than the pressure Pd2.

The horsepower control unit 30 is a horsepower control unit 31 for adjusting the swash plate angle of the hydraulic pump 20 in accordance with the pilot pressure input from the pilot pump 33; And an electromagnetic proportional pressure reducing valve 32 for varying an opening amount of a flow path connecting the pilot pump 33 and the horsepower control unit 31 according to the magnitude of the current command value input from the equipment controller 62. .

In addition, the power control device according to another aspect of the present invention for controlling the hydraulic pump 20 driven by the engine 10, by varying the swash plate angle of the hydraulic pump 20, the hydraulic pump 20 Horsepower control unit 30 for varying the horsepower required; A pressure sensor 50 for detecting a load pressure Pd of the hydraulic oil discharged from the hydraulic pump 20; And calculating a target pump required horsepower from the load pressure Pd sensed by the pressure sensor 50, and the required horsepower of the hydraulic pump 20 gradually increases to the target pump required horsepower for a predetermined time Δt. It includes a control unit 60 for controlling the horsepower control unit 30 to approach.

According to an embodiment of the present invention, when the load pressure Pd sensed from the pressure sensor 50 is the no-load pressure Pd1, the target pump required horsepower is set to the minimum horsepower POmin, and the pressure sensor When the load pressure sensed from 50 is the maximum set pressure Pd2, the target pump required horsepower is set to the maximum horsepower POmax, and the maximum set pressure Pd2 is the maximum horsepower of the hydraulic pump 20 It is less than or equal to the pressure Pd2 at the starting point of back horsepower control of POmax).

In addition, the predetermined time Δt is proportional to the horsepower difference value ΔPO between the current pump required horsepower and the target pump required horsepower of the hydraulic pump 20.

The horsepower control unit 30 is a horsepower control unit 31 for adjusting the swash plate angle of the hydraulic pump 20 in accordance with the pilot pressure input from the pilot pump 33; And an electromagnetic proportional pressure reducing valve 32 for varying an opening amount of a flow path connecting the pilot pump 33 and the horsepower control unit 31 according to the magnitude of the current command value input from the controller 60.

On the other hand, the object as described above is a power control method of a construction machine for controlling the hydraulic pump 20 driven by the engine 10, the step of calculating the current pump required horsepower of the hydraulic pump 20; Calculating a target pump required horsepower from the load pressure Pd of the hydraulic oil discharged from the hydraulic pump 20; And gradually approaching the required horsepower of the hydraulic pump 20 from the current pump required horsepower to the target pump required horsepower for a predetermined time Δt for a predetermined time (Δt). Can be achieved.

According to an embodiment of the present disclosure, the power control method may further include calculating the predetermined time Δt from the horsepower difference value ΔPO of the current pump required horsepower and the target pump required horsepower. .

According to the problem solving means described above, by calculating the engine speed command value corresponding to the engine load ratio and outputting it to the engine, it is possible to maintain the engine rotation speed at the target rotation speed, thereby improving the fuel efficiency of the construction machine And vibration can be reduced.

In addition, the equipment control unit that receives the engine load ratio from the engine control unit calculates the engine rotation speed command value and outputs it to the engine control unit, thereby distributing the calculation load and facilitating application of the power control device of the present invention to an existing system. .

In addition, by gradually changing the required horsepower of the hydraulic pump in accordance with the load pressure, it is possible to prevent the hydraulic shock caused by the time delay of the conventional horsepower control time. In addition, by preventing the hydraulic shock, it is possible to prevent the engine rotational speed is sharply lowered by the hydraulic pump load, thereby minimizing the amount of smoke and vibration of the engine.

In addition, there was a problem in that the required horsepower of the hydraulic pump is sharply decreased to reduce the workability of the construction machine in order to restore the engine rotation speed, but by gradually bringing the required horsepower of the hydraulic pump to the target pump required horsepower gradually for a predetermined time. And, it is not necessary to restore the rotational speed of the engine, which can prevent the required horsepower of the hydraulic pump is reduced, thereby improving the workability of the construction machine.

In particular, when the load pressure Pd is the no-load pressure Pd1, the target pump required horsepower is set to the minimum horsepower (POmin) to minimize the load applied to the engine by the hydraulic pump, thereby improving fuel economy. .

In addition, by setting the maximum set pressure Pd2 at which the target pump required horsepower becomes the maximum horsepower POmax to be less than or equal to the pressure Pd2 of the back horsepower control start point of the maximum horsepower POmax of the hydraulic pump, When the horsepower reaches the target pump required horsepower, the discharge flow rate of the hydraulic pump can be as large as possible, thereby further improving workability.

Further, by setting the predetermined time Δt to be proportional to the horsepower difference value ΔPO of the current pump required horsepower and the target pump required horsepower of the hydraulic pump, if the horsepower difference value ΔPO is small, the horsepower is quickly controlled. If the horsepower difference value (ΔPO) is large, it is possible to secure a sufficient control time such that the hydraulic shock does not occur.

On the other hand, by configuring the horsepower control unit with the electronic proportional pressure reducing valve for varying the opening amount of the flow path connecting the horsepower control unit, the pilot pump and the horsepower control unit, it is possible to apply the spirit of the present invention to a general hydraulic system universally .

1 is a graph schematically showing a pump discharge flow rate and required horsepower, an engine output and a rotation speed, and a horsepower control current command value change according to an existing power control device under sudden operation conditions of an operation unit;

FIG. 2 is a graph showing a control process of FIG. 1 in a pressure-flow diagram (back horsepower diagram) of a hydraulic pump;

3 is a graph schematically showing the engine rotation speed according to the conventional engine load ratio;

4 is a conceptual diagram schematically showing a power control apparatus for a construction machine according to an embodiment of the present invention;

5 is a graph schematically showing an engine rotation speed command value according to an engine load ratio set in the equipment control unit of FIG. 4;

6 is a graph schematically showing the engine rotation speed according to the engine load ratio of the engine controlled by the power control device shown in FIG.

7 is a flow chart schematically showing a power control process by the power control device shown in FIG.

8 is a graph schematically showing a target pump required horsepower and a current command value with respect to a load pressure set in the controller of FIG. 3;

FIG. 9 is a graph schematically illustrating a rise time with respect to a horsepower difference value between a target pump power required and a current pump power required by the controller of FIG. 3;

FIG. 10 is a graph schematically illustrating a horsepower increase rate with respect to a specific horsepower difference value set in the controller of FIG. 4;

11 is a graph schematically showing the maximum and minimum horsepower curves of the hydraulic pump shown in FIG. 4;

12 is a graph schematically showing the pump discharge flow rate and required horsepower, engine output and rotation speed in accordance with the power control device shown in FIG.

FIG. 13 is a graph showing a control process of FIG. 12 in a pressure-flow diagram (back horsepower diagram) of a hydraulic pump;

14A is a graph illustrating measurement of the boom rising speed and the engine rotation speed according to the control process of FIG. 1;

FIG. 14B is a graph illustrating measurement of a boom rising speed and an engine rotation speed according to the control process of FIG. 12.

10; Engine 20; Hydraulic pump

30; Horsepower control unit 31; Horsepower regulator

32; Electromagnetic proportional pressure reducing valve 33; Pilot pump

40; Regulator 50; Pressure sensor

60; Control unit 61; Engine control unit

62; Equipment control unit ΔPO; Horsepower difference

Δt; Rise time, preset time POmin; Pump minimum horsepower

POmax; Pump maximum horse power Pd; Load pressure

Pd1; No load pressure Pd2; Set pressure

Hereinafter, with reference to the accompanying drawings will be described in detail a power control apparatus for a construction machine according to an embodiment of the present invention.

Referring to FIG. 4, a power control apparatus for a construction machine according to an embodiment of the present invention includes an engine 10 for driving a hydraulic pump 20 and a swash plate of the hydraulic pump 20 according to an input horsepower control signal. A horsepower control unit 30 for varying the required horsepower of the hydraulic pump 20 by varying the angle, a pressure sensor 50 for detecting the pressure of the hydraulic oil discharged from the hydraulic pump 20, and the horsepower control unit And a control unit 60 for outputting the horsepower control signal to the 30 and controlling the rotation speed of the engine.

The controller 60 includes an engine controller 61 and an equipment controller 62 such as an ECU (Electronic Control Unit).

The engine controller 61 outputs a fuel injection amount command value to the engine 10 to control the rotation speed of the engine 10. In addition, the engine control unit 61 calculates the load torque of the engine from the current fuel injection amount command value and the current rotation speed of the engine. In addition, the maximum torque of the engine for each rotational speed is set in the engine. Therefore, when the target rotational speed of the engine is input from the dial gauge 11, the engine control unit 61 may calculate the maximum torque of the engine corresponding to the target rotational speed. In addition, the engine control unit 61 calculates and outputs the engine load ratio, which is the ratio of the load torque to the maximum torque, to the equipment control unit 62.

In the equipment control unit 62, as shown in FIG. 5, an engine rotational speed command value for an engine load ratio for maintaining the rotational speed of the engine 10 at the input target rotational speed is set. Here, when the target rotational speed is variable, the engine rotational speed command value with respect to the engine load ratio is also variable. Therefore, the set value as shown in FIG. 5 is set differently according to the magnitude of the target rotational speed of the engine. That is, the set values as shown in FIG. 5 are set for each target rotational speed of the engine and stored in the memory or the equipment controller 62.

Therefore, when the target rotational speed of the engine is input to the equipment control unit 62, the equipment control unit 62 selects a pattern corresponding to the input target rotational speed among the patterns shown in FIG. Thereafter, the equipment controller 62 calculates and outputs an engine speed command value corresponding to the engine load factor input from the selected pattern to the engine controller 61. Then, the engine control unit 61 calculates and outputs the fuel injection amount command value corresponding to the engine rotation speed command value to the engine 10. As a result, the rotational speed of the engine is controlled. At this time, as shown in Figure 5, the engine speed command value increases as the engine load ratio increases. That is, when the load applied to the engine 10 from the hydraulic pump 20 increases, the fuel injection amount of the engine 10 increases, and when the load applied to the engine 10 from the hydraulic pump 20 decreases, the fuel injection amount Becomes smaller.

As a result, by controlling the fuel injection amount so as to increase the torque in accordance with the load ratio of the engine, the rotational speed of the engine 10 can be kept constant at the target rotational speed as shown in FIG.

Hereinafter, the rotation speed control method of the engine having the configuration as described above will be described in detail.

Referring to FIG. 7, first, when an engine target rotation speed is set from the dial gauge 11, the engine target rotation speed is transmitted to the engine controller 61 and the equipment controller 62 (S110).

Then, the engine control unit 61 calculates the engine maximum torque for the input engine target rotational speed and calculates the current engine load torque (S120). After that, the engine control unit 61 calculates the engine load ratio (S130). The engine load factor is calculated by the following equation.

Equation 1

When the engine load factor is calculated, the engine controller 61 outputs the calculated engine load factor to the equipment controller 62.

On the other hand, the equipment control unit 62, when the engine target rotational speed is input from the dial gauge 11, the engine rotational speed command value according to the engine load ratio as shown in Figure 5 is set based on the input engine target rotational speed Select a pattern. Thereafter, the equipment control unit 62 calculates an engine speed command value corresponding to the engine load ratio output from the engine control unit 61 from the selected pattern as shown in FIG. 5 (S140). After that, the equipment control unit 62 outputs the calculated engine speed command value to the engine control unit 61. Then, the engine control unit 61 calculates a fuel injection amount command value from the input engine rotation speed command value and outputs it to the engine 10 (S150).

The power control device and the power control method have been described through the rotational speed control of the engine. Hereinafter, the power control device and the power control method through the control of the hydraulic pump 20 will be described.

Referring to FIG. 4, the hydraulic pump 20 is a variable pump having a variable discharge flow rate due to the inclination of the swash plate 23. The hydraulic pump 20 includes a regulator 40 for adjusting the swash plate 23. To be prepared.

The regulator 40 has a working horsepower control unit 41 for varying the discharge flow rate of the hydraulic pump 20 in accordance with a signal for the operation amount of the operation unit 42, and the horsepower required of the hydraulic pump 20 is constant It includes a horsepower control unit 43 for maintaining as, and a horsepower control unit 31 for adjusting the required horsepower of the hydraulic pump 20.

The working flow rate adjusting unit 41 is for adjusting the discharge flow rate of the hydraulic pump 20 according to a signal corresponding to the operation signal of the operation unit 42, and is proportional to the magnitude of the operation signal of the operation unit 42. The discharge flow rate of the hydraulic pump 20 is increased. Here, the signal corresponding to the operation signal of the operation unit 42 is the negative pressure that is the bypass pressure passing through the main control valve 21, the posicon pressure which is a pilot pressure according to the operation of the operation unit 42 and each It may be composed of a signal for any one selected from the load sensing pressure of the actuator 22.

The back horsepower control unit 43 adjusts the discharge flow rate of the hydraulic pump 20 according to the discharge pressure of the hydraulic pump 20 to maintain the required horsepower of the hydraulic pump 20. Here, the back horsepower is variable by the horsepower control unit 31. Accordingly, the back horsepower control unit 43 adjusts the discharge flow rate of the hydraulic pump 20 along the variable back horsepower diagram of the current state.

The horsepower control unit 31 is for changing the required horsepower of the hydraulic pump 20, the pilot pressure discharged from the pilot pump 33 is applied. Here, the electromagnetic proportional pressure reducing valve 32 is installed between the horsepower control part 31 and the pilot pump 33, and the pilot pump 33 and the horsepower control part by the electromagnetic proportional pressure reducing valve 32. The opening degree of the flow path which connects between 31 is adjusted. The electromagnetic proportional pressure reducing valve 32 is converted according to the current command value output from the equipment control unit 62. Therefore, the horsepower control unit 31 is to change the swash plate angle of the hydraulic pump 20 in accordance with the current command value output from the equipment control unit 62.

In this embodiment, the horsepower control unit 31 and the electromagnetic proportional pressure reducing valve 32 is defined as a horsepower control unit 30, unlike the embodiment is the horsepower control unit 31 and the electromagnetic proportional pressure reduction The valve 32 may be implemented as one electromagnetic proportional pressure reducing valve in the electronically controlled pump. Therefore, the horsepower control unit 30 may not only be composed of the horsepower control unit 31 and the electromagnetic proportional pressure reducing valve 32 but also may be composed of one electromagnetic proportional pressure reducing valve in the electronically controlled pump.

Looking at the operation process of the horsepower control unit 30 in more detail, when the high current command value (for example, 600mA) output from the equipment control unit 62 to the electromagnetic proportional pressure reducing valve 32 The valve 32 increases the opening amount of the flow path between the pilot pump 33 and the horsepower control unit 31. Then, the horsepower control unit 31 adjusts the swash plate angle to reduce the discharge flow rate of the hydraulic pump 20 to reduce the required horsepower of the hydraulic pump 20.

Contrary to the above, when the low current command value (for example, 200 mA) is output to the electromagnetic proportional pressure reducing valve 32, the electromagnetic proportional pressure reducing valve 32 is the pilot pump 33 and the horsepower control part 31. Reduce the opening amount of the flow path. Then, the horsepower control unit 31 increases the horsepower of the hydraulic pump 20 by adjusting the swash plate angle so that the discharge flow rate of the hydraulic pump 20 increases.

The pressure sensor 50 detects the discharge pressure of the hydraulic pump 20 and transmits it to the equipment controller 62. The discharge pressure of the hydraulic pump 20 may be represented as a load pressure because it may vary depending on the load transmitted from the actuator 22 through the main control valve 21.

The equipment control unit 62 performs the following control function in addition to the engine rotation speed control described above.

The equipment control unit 62 calculates a current command value to be output to the electromagnetic proportional pressure reducing valve 32 and outputs it to the electromagnetic proportional pressure reducing valve 32. More specifically, the equipment control unit 62 is set to the target pump required horsepower for the load pressure (Pd) detected by the pressure sensor 50 as shown in FIG. Here, the target pump required horsepower may be converted into a current command value output to the electromagnetic proportional pressure reducing valve 32. Since the system of the present embodiment is a negative system in which the required horsepower of the hydraulic pump 20 rises in inverse proportion to the current command value, in FIG. 8, the magnitudes of the current command value and the target pump required horsepower vary in opposite directions depending on the load pressure Pd.

Moreover, the pump horsepower increase / decrease rate is set in the said equipment control part 62 like FIG. The pump horsepower increase and decrease rate of FIG. 9 represents a time for increasing the current pump required horsepower from the hydraulic pump 20 to the target pump required horsepower, and the larger the horsepower difference value ΔPO between the current pump required horsepower and the target pump required horsepower, the pump. The horsepower rise time is set to be large. In addition, in the equipment control unit 62, the pump required horsepower increase rate with respect to the selected specific rise time Δt1 is set as shown in FIG. Pump horsepower increase rate as shown in Figure 10 may be stored in the form of a table for the rise time as a value respectively set according to the size of the rise time.

As described above, when the load pressure Pd is input from the pressure sensor 50, the equipment controller 62 calculates a target pump required horsepower from the set value as shown in FIG. 8. Thereafter, the equipment control unit 62 calculates a horsepower difference value ΔPO between the current pump required horsepower of the hydraulic pump 20 and the calculated target pump required horsepower. The current pump required horsepower of the hydraulic pump 20 may be calculated from the load pressure Pd sensed by the pressure sensor 50 and the swash plate angle of the current hydraulic pump 20.

When the horsepower difference value ΔPO is calculated, the equipment controller 62 calculates the rise time Δt from the pump horsepower increase and decrease rate as shown in FIG. 9. When the rise time Δt is calculated, the horsepower increase rate as shown in FIG. 10 is calculated.

When the calculation of the horsepower increase rate is completed, the equipment control unit 62 raises the current pump required horsepower to the target pump required horsepower at the calculated rise rate during the calculated rise time Δt. That is, the equipment control unit 62 gradually raises the required horsepower of the hydraulic pump 20 to the target pump required horsepower for a predetermined time.

Meanwhile, as shown in FIG. 8, the target pump required horsepower is set to the minimum horsepower POmin when the load pressure Pd sensed by the pressure sensor 50 is the no load pressure Pd1, and the load pressure. If Pd is the maximum set pressure Pd2, the maximum horsepower POmax is set. At this time, as shown in Figure 11, the maximum set pressure (Pd2) is set equal to or less than the horsepower control starting point (Pd2) of the maximum horsepower (POmax) of the hydraulic pump 20, which is the hydraulic pump ( When the required horsepower of 20) reaches the target pump required horsepower, the discharge flow rate of the hydraulic pump 20 is secured as large as possible to improve the working performance of the construction machine.

Hereinafter, the power control method through the hydraulic pump control having the configuration as described above will be described in detail.

Referring to FIG. 12, first, in a state in which there is no operation amount of the operation unit 42, the load pressure Pd sensed by the pressure sensor 50 is the no load pressure Pd1. When the no-load pressure Pd1 signal is transmitted to the equipment control unit 62, the equipment control unit 62 calculates the target pump required horsepower as the minimum horsepower POmin from FIG. 8 to maximize the electromagnetic proportional pressure reducing valve 32. The current command value (for example, 600 mA) is output. Then, the electromagnetic proportional pressure reducing valve 32 opens the opening amount of the flow path connecting the horsepower control unit 31 and the pilot pump 33 to the maximum, whereby the horsepower control unit 31 opens the hydraulic pump 20. Run at minimum horsepower (POmin).

In this state, as shown in FIG. 12, when the operation amount of the operation unit 42 is rapidly increased, a signal for the operation amount is applied to the working flow rate adjusting unit 41. Then, the working flow rate adjusting unit 41 rapidly increases the flow rate of the hydraulic pump 20. However, even if the flow rate increases sharply, since the horsepower control unit 31 drives the hydraulic pump 20 to the minimum horsepower POmin, the flow rate does not increase rapidly or the load pressure Pd increases as in the prior art. However, in order to increase the driving force of the work device, it is necessary to increase the required horsepower of the hydraulic pump 20 through the horsepower control unit 31.

To this end, the equipment control unit 62 receives the increased load pressure Pd sensed by the pressure sensor 50 and calculates a target pump required horsepower according to the load pressure Pd received from the set value as shown in FIG. 8. . Then, the equipment control unit 62 calculates the horsepower difference value ΔPO of the current pump required horsepower and the target pump required horsepower of the hydraulic pump 20, and the horsepower difference value calculated from the set values shown in Figs. 9 and 10. The rise time Δt and the rise rate with respect to ΔPO are calculated. Thereafter, the equipment control unit 62 gradually increases the current pump required horsepower to the target pump required horsepower calculated at the rising rate calculated during the rise time Δt.

As such, the equipment control unit 62 gradually raises the required horsepower of the hydraulic pump 20 to the target pump required horsepower calculated from the minimum horsepower POmin, so that the hydraulic shock does not occur as shown in FIG. 12. do. In addition, as shown in Figure 12, it is possible to minimize the amount of smoke by preventing a sharp drop in the rotational speed of the engine, as well as to reduce the vibration caused by the engine speed decrease.

On the other hand, conventionally, when the engine rotational speed is lower than the target engine rotational speed set from the dial gauge 11, the horsepower control to lower the horsepower required of the hydraulic pump 20 to the minimum to reduce the workability of the construction machine, this embodiment In the example, the degree of reduction in the rotational speed of the engine is small, and the workability of the construction machine can be improved by gradually increasing the required horsepower of the hydraulic pump 20 from the minimum horsepower to the target pump required horsepower.

Referring to FIG. 13, a process of raising the hydraulic pump 20 from the minimum horsepower POmin to the target pump horsepower is schematically illustrated in a pressure-flow diagram (back horsepower diagram). Referring to FIG. 13, the equipment control unit 62 raises the required horsepower of the hydraulic pump 20 during the rise time Δt from the minimum horsepower POmin to the target pump required horsepower, and the horsepower during the rise time Δt. The adjusting unit 43 performs back horsepower control along a variable back horsepower diagram. As such, as the horsepower control and the horsepower control of the hydraulic pump 20 are performed at the same time, the horsepower, the flow rate and the load pressure are changed in the diagram as shown in FIG. 13, thereby preventing the hydraulic shock as shown in FIG. 2. It can be seen.

Figure 14a shows the boom rising speed and the engine rotational speed by the conventional power control device, Figure 14b shows the amount of change in the boom rising speed and the engine rotational speed by the power control device according to this embodiment.

Referring to FIG. 14A, in the related art, the boom rising speed is rapidly increased due to the rapid flow rate and load pressure. However, due to the hydraulic shock, the engine rotational speed is drastically lowered, as in the E region, and thus horsepower control is started to lower the required horsepower of the hydraulic pump 20 to the minimum horsepower. As a result, a section in which the boom rising speed is rather reduced occurs in the D region. As a result, not only the workability of the construction machine is very deteriorated, but also the amount of smoke and the vibration are large.

However, referring to FIG. 14B, in the present embodiment, the increase rate of the boom ascending speed is somewhat lower than that of FIG. 14A, but the boom ascending speed is not lowered in the F section and the engine rotational speed is not significantly reduced as in the G section. . As a result, it is possible not only to improve the workability of construction machinery but also to minimize the generation of soot and vibration.

On the other hand, when the load pressure does not vary by rising to the reference pressure, horsepower control of the hydraulic pump 20 can be performed in consideration of the engine rotation speed. In addition, even when a change in load pressure occurs and the engine rotational speed is changed, horsepower control of the hydraulic pump 20 may be performed in consideration of the engine rotational speed.

Claims

An engine 10 connected to the hydraulic pump 20 to drive the hydraulic pump 20; And

An engine load ratio defined by a ratio of the load torque of the engine to the engine maximum torque calculated from the input engine target rotational speed is calculated, and the engine rotational speed command value according to the engine load ratio to drive the engine at the target rotational speed And a control unit (60) which calculates and outputs the output to the engine.
The method of claim 1,

The control unit 60,

The engine maximum torque is calculated from the engine target rotational speed, the engine load torque is calculated from the fuel injection amount command value output to the engine 10, and the engine load ratio is calculated from the calculated engine maximum torque and the engine load torque. An engine control unit 61 which calculates and outputs the output; And

An equipment control unit 62 for calculating the engine speed command value from the engine load ratio output from the engine control unit 61 and outputting the engine speed command value to the engine control unit 61;

The engine control unit (61) calculates the fuel injection amount command value according to the engine rotation speed command value transmitted from the equipment control unit (62) and outputs to the engine (10).
The method of claim 2,

A horsepower control unit (30) for varying horsepower of the hydraulic pump (20) by varying the swash plate angle of the hydraulic pump (20); And

Further comprising a pressure sensor 50 for detecting the load pressure (Pd) of the hydraulic oil discharged from the hydraulic pump 20,

The equipment controller 62 calculates a target pump required horsepower from the load pressure Pd sensed by the pressure sensor 50, and the required horsepower of the hydraulic pump 20 is the target horsepower for a predetermined time Δt. Power control device for a construction machine, characterized in that for controlling the horsepower control unit 30 to gradually approach the pump horsepower.
The method of claim 3,

When the load pressure Pd sensed by the pressure sensor 50 is the no load pressure Pd1, the target pump required horsepower is set to the minimum horsepower POmin,

If the load pressure sensed from the pressure sensor 50 is the maximum set pressure Pd2, the target pump required horsepower is set to the maximum horsepower POmax,

The maximum set pressure (Pd2) is a power control device for a construction machine, characterized in that less than or equal to the pressure (Pd2) of the starting horsepower control starting point of the maximum horsepower (POmax) of the hydraulic pump (20).
According to claim 3, The horsepower control unit 30,

A horsepower control unit 31 for adjusting the swash plate angle of the hydraulic pump 20 according to the pilot pressure input from the pilot pump 33; And

It includes an electronic proportional pressure reducing valve 32 for varying the opening amount of the flow path connecting the pilot pump 33 and the horsepower control unit 31 according to the magnitude of the current command value input from the equipment control unit 62 A power control device for a construction machine.
In the power control device of the construction machine for controlling the hydraulic pump 20 driven by the engine 10,

A horsepower control unit (30) for varying horsepower of the hydraulic pump (20) by varying the swash plate angle of the hydraulic pump (20);

A pressure sensor 50 for detecting a load pressure Pd of the hydraulic oil discharged from the hydraulic pump 20; And

The target pump required horsepower is calculated from the load pressure Pd sensed by the pressure sensor 50, and the required horsepower of the hydraulic pump 20 is gradually approached to the target pump required horsepower for a predetermined time Δt. Power control device for a construction machine, characterized in that it comprises a control unit (60) for controlling the horsepower control unit (30).
The method of claim 6,

When the load pressure Pd sensed by the pressure sensor 50 is the no load pressure Pd1, the target pump required horsepower is set to the minimum horsepower POmin,

If the load pressure sensed from the pressure sensor 50 is the maximum set pressure Pd2, the target pump required horsepower is set to the maximum horsepower POmax,

The maximum set pressure (Pd2) is a power control device for a construction machine, characterized in that less than or equal to the pressure (Pd2) of the starting horsepower control starting point of the maximum horsepower (POmax) of the hydraulic pump (20).
The method of claim 6,

The predetermined time period Δt is proportional to the horsepower difference value ΔPO of the current pump required horsepower and the target pump required horsepower of the hydraulic pump (20).
The method of claim 6,

The horsepower control unit 30,

A horsepower control unit 31 for adjusting the swash plate angle of the hydraulic pump 20 according to the pilot pressure input from the pilot pump 33; And

It characterized in that it comprises an electromagnetic proportional pressure reducing valve 32 for varying the opening amount of the flow path connecting the pilot pump 33 and the horsepower control unit 31 according to the magnitude of the current command value input from the control unit 60 Power control system for construction machinery.
In the power control method of the construction machine for controlling the hydraulic pump 20 driven by the engine 10,

Calculating a current pump required horsepower of the hydraulic pump 20;

Calculating a target pump required horsepower from the load pressure Pd of the hydraulic oil discharged from the hydraulic pump 20; And

And gradually approaching the required horsepower of the hydraulic pump (20) from the current pump required horsepower to the target pump required horsepower for a predetermined time (Δt).
The method of claim 10,

And calculating the predetermined time Δt from the horsepower difference value ΔPO between the current pump required horsepower and the target pump required horsepower.